Study setting
This study was conducted in April 2016 in Humbo district, Southern Ethiopia. The district has 39 rural and 5 urban kebeles (the smallest administrative unit in Ethiopia having approximately 1,000 households). Humbo has a total population of 157,073 of which children 6-59 months of age contribute to 11% of the population. In the district there are 6 health centres and 39 health posts. About 78 health extension workers (HEWs) are deployed in the health posts and are providing community-based service including distribution of VAS. HEWs are cadres of trained female community-based health workers who received at least one year of training after completing secondary education. In each kebele, on average 2 HEWs are deployed. In every kebele, a network of volunteers, called the Health Development Army (HDA) members support HEWs through community mobilization.
In Ethiopia VAS is distributed through three strategies: Enhanced Outreach Strategy (EOS), Community Health Days (CHDs) and the routine Health Extension Program (HEP). The EOS is a makeshift strategy involving distribution of the supplement via centrally organized semi-annual or quarterly campaigns along with deworming and screening for malnutrition. The CHD is a similar modality as that of the EOS except that campaigns are organized at kebele level. The CHD is considered as a transitional stage to the ultimate integration of VAS into the HEP. In the third strategy, VAS is considered as the integral component of the HEP and the supplement is provided by HEWs through a mixture of static service, locally organized campaigns and home visits. In Humbo district, at the time of the survey VAS was mainly distributed via the third option – distribution through routine HEP.
Study design
We implemented quantitative cross-sectional survey in April 2016 in Humbo district. The source population for the study was all children 6-59 months of age residing in the rural kebeles of the district; whereas, the study population was similar group of children residing in randomly selected six kebeles of Humbo district.
Sample size and sampling procedure
A sample size of 840 was calculated using single population proportion formula with the inputs of 95% confidence level, 5% margin of error, 53.1% expected coverage of VAS [12] design effect of 2 and 10% compensation for possible non-response.
The study subjects were identified using multistage cluster sampling approach. Initially, the 39 rural kebeles found in the district were categorized as accessible (30 kebeles) and non-accessible (9 kebeles) based on a cut-off distance of 10 kms from the nearest major all-weather roads. Then, accessible and non-accessible kebeles were separately listed and, four and two kebeles were randomly selected from the two strata, respectively. The total sample size of 840 was allotted to each of the six kebeles proportional to their population size and the sample size distributed per kebele ranged from 116 to 174 children. Ahead of the study, complete listing of eligible children was made and used as a sampling frame. Ultimately the required subjects were selected using systematic random sampling technique.
Data collection tools
Data were collected in April 2016 using pre-tested and structured questionnaire developed by the investigators specifically for the study. The questionnaire used in the study is provided as supplementary file with this manuscript (Supplementary File 1). The questionnaire was developed in English and translated to the local Wolaitigna language. Socio-demographic and economic related information were collected using questions extracted from the standard DHS questionnaire. The DHS questionnaire is a standard tool designed to collect demographic and health data consistently in multiple low-income countries. We collected the data using experienced and trained enumerators and supervisors. The VAS status of the selected child was determined by showing the mother/caregiver a VAS capsule and asking whether the child had received a similar one in the past 6 months.
Variables of the study
The dependent variable of the study was the recent (last 6 months) vitamin A supplementation status of the child. The independent variables were selected based on previous literature [5,11,12] and include socio-demographic variables (maternal age, maternal and paternal educational status, household wealth index, family size, age and sex of the child), type of the household (whether the household had been considered as model or non-model household by local HEWs), distance from the nearest health facility, whether the respondent received health education about vitamin A supplement in the last 12 months or not, knowledge about at least one benefit of vitamin A supplements to children, knowledge about at least one consequence of VAD and knowledge about dietary sources of vitamin A. According to the HEP of Ethiopia, model households are families that successfully implemented all the packages of the health extension program with the support of the community health workers.
Data processing and analysis
The data were entered, cleaned and analyzed using SPSS for windows, version 20. Frequencies, percentage, mean and standard deviation were used to summarize the data.
Bivariable logistic regression analysis was performed to assess the association of each predictor with the outcome variable and multivariable logistic model was to control the effect of confounders. Variables with p-value less than 0.25 in the bivariable models were considered as candidate variables for the multivariable analysis [14]. In the multivariable analysis, proximate and distal variables were fitted separately in order to avoid over-adjustment bias [15]. The distal variables considered in the analysis were: household wealth index, maternal and paternal educational status, household type (being model or non-model household), sex and birth order of the baby. On the other hand, the proximate variables were: knowledge on vitamin A and VAS, physical access to the nearby health institution, exposure to VAS promotion activities and age of the child. Fitness of the logistic model was checked using Hosmer and Lemeshow statistic. Absence of multicollinearity was checked following standard approaches. The outputs of the analysis are presented using crude (COR) and adjusted odds ratio (AOR) with the 95% confidence interval (CI).
Wealth index was constructed as an indicator of household economic status based on variables related to housing conditions, ownership of household assets, type of drinking water source, size of agricultural land, and number of livestock owned. Principal component analysis (PCA) was performed to generate a summary wealth index score and the score was ultimately categorized into three tertiles: poor, medium and rich.
Ethical considerations
The study was approved by the ethics committee at Hawassa University, College of Medicine and Health Science. Data were collected after security informed verbal consent from the primary caregivers of the study children. Verbal, rather that written consent was used because significant proportion of the population in the area had no formal education. The same was approved by the ethics committee that reviewed the protocol.